The servicing work, installation work and repair work of an object to be serviced, such as a wind power station, an oil drilling platform, a lighthouse, et cetera, usually requires that the object comprises an elevator, with which it is possible to move and to lift a load in the vertical direction. The structure of this type of elevator can vary, but the elevator usually comprises an elevator car, a lifting platform or corresponding load-receiving part, with which a load is transferred. The load-receiving part is suspended on a hoisting member that is continuous in the vertical direction, such as on a hoisting rope or hoisting belt. The load-receiving part is moved along a vertical trajectory guided by a guide rail, a guide cable or corresponding. In some embodiments the hoisting member is also used as the guide rail/guide cable of the load-receiving part.
The driving force for moving the load-receiving part is usually produced with an electric drive. The electric drive comprises a hoisting machine, which comprises an electric motor. The driving force is transmitted from the electric motor to the hoisting member with e.g. a traction sheave or drum, driven by friction or by gears, of the hoisting machine. The traction sheave/drum is fixed to the rotating rotor or shaft of the electric motor. In addition, the hoisting machine can comprise one or more controllable machinery brakes, which engage with the shaft or traction sheave/drum to brake the movement of the traction sheave/drum. Supply of the driving power to the electric motor occurs e.g. with a frequency converter belonging to the electric drive or with a power supply device comprising other controllable solid-state switches.
The electric drive is conventionally disposed in a fixed manner in a site in connection with the rest of the elevator. In many of the aforementioned sites the elevator is regularly exposed to the outside air or to other corresponding environmental stressing. Owing to this, atmospheric moisture, salinity, cold, heat, solar radiation, wind, dirt and many other factors cause lifetime problems especially for the electric drive, control cards and other particularly sensitive components. It is quite normal that a serviceman arriving at a site must, before starting the actual servicing jobs, repair the elevator to working condition. Since many of the sites are located at the end of difficult transport connections, spare parts deliveries are also slow, slowing down servicing jobs and thus causing extra costs and standstills. Additionally, e.g. wind farms can comprise up to hundreds of turbine towers, each of which comprises a separate elevator with electric drive. Each aforementioned elevator in this case forms a potential reliability problem slowing down servicing.
For solving the problem an elevator can be protected by covering and/or proofing the operating environment of the elevator against the aforementioned environmental stresses. This, however, incurs additional costs and is otherwise often unreasonably awkward precisely because of, inter alia, the awkward transport connections. In addition, protection in different operating sites essentially intended to be open can even be impossible.